Code reading apparatus having optimal battery voltage detection function

ABSTRACT

An illumination section illuminates a code on a recording medium, on which data about audio information is recorded as an optically readable code, by repeatedly emitting light at predetermined intervals. An image sensing section receives each of light beams reflected by the recording medium including the code illuminated by the illumination section in a read/scan operation for the code, and outputs a corresponding image sensing signal. A signal processing section decodes the data about the audio information by processing the image sensing signal output from the image sensing section. A reproduction output section reproduces the audio information on the basis of the data decoded by the signal processing section and outputs the information. A supply voltage detection section detects a supply voltage to a power supply circuit system including a battery used as a power supply of the apparatus. A detection timing control section controls the supply voltage detection section to detect the supply voltage at a predetermined timing in image sensing operation performed by the image sensing section at the time of light emission after the supply voltage to the power supply circuit system is turned on by a power switch and first light emission is performed by the illumination section.

BACKGROUND OF THE INVENTION

The present invention relates a code reading apparatus for opticallyreading a code on a recording medium on which data about audioinformation and the like is printed/recorded as an optically readablecode.

A code reading apparatus like the above one proposed by the assignee ofthe present invention is disclosed in Jpn. Pat. Appln. KOKAI PublicationNo. 6-231466 (EP No. 0,670,555A1), which includes a dot code as a codeobtained by printing/recording data about audio information, videoinformation, text data, and the like on a printing medium such as apaper sheet in an optically readable form, and a code reading apparatusthat is manually operated to scan the dot code to optically read it, andreproduces/outputs information such as original audio information.

FIGS. 9A and 9B show the physical format of the dot code.

A plurality of blocks 30 are two-dimensionally arranged side by side toform a dot code 31. Each block 30 is composed of a data area 32 in whichpart of data about audio information or the like which corresponds toone of the blocks obtained by dividing the data is present as a dotimage made up of white or black dots, each corresponding to "0" or "1",in a predetermined form, makers 33, each having a predetermined numberof consecutive black dots, arranged on the four corners of the block 30to be used to detect a reference point for detection of the respectivedots in the data area 32, and block address patterns 34 that includeerror detection or error correction codes and are arranged between themarkers 33 to identify each block 30 when the above different blocks 30are read.

Note that the lines drawn in the form of a matrix are imaginary linesexpressing the matrix.

Assume that the size of the image sensing plane of a solid-state imagesensing device of a reading apparatus is smaller than the overall sizeof a dot code having such a physical format, i.e., the whole dot codecannot be sensed by the solid-state image sensing device with one shot.Even in this case, if the address assigned to each of the above blockscan be read and recognized, the original data can be decoded from thedata of the respective blocks on the basis of the addresses.Consequently, a large amount of data that cannot be expressed by a knownone- or two-dimensional bar code can be held on a paper sheet or thelike. This technique facilitates data transfer through media such as apaper sheet, and hence is expected to have a variety of applicationsthat are not conceivable in the prior art.

The above code reading apparatus used in this case performs so-calledpulse emission, i.e., repeatedly emitting light at predeterminedintervals by using an illumination means such as an LED in read/scanoperation. Since the exposure time in image sensing operation issubstantially determined by the emission intervals, various problems inread operation due to the influences of camera shake and the like can besolved, thus providing advantages in read operation by manual scanning.

In a code reading apparatus of this type, since a compact battery isused as a power supply, a battery voltage detection function isindispensable as in other types of electronic devices using compactbatteries.

In addition, an LED or the like used as the above illumination means andthe solid-state image sensing device consume a large amount of current,and the current consumption of the apparatus sequentially changes in itsoperation sequence.

In general, when the battery voltage of an electronic device using acompact battery is to be detected, the degree of consumption of thebattery is detected after the power is turned on, and the user isimmediately warned of the detection result.

As shown in FIG. 10, the voltage of a battery 1 is monitored by avoltage detection circuit 2 through a power switch 14. When themonitored voltage becomes equal to or lower than a predetermined level,the voltage detection circuit 2 outputs an L-level signal. Uponreception of this signal, a system controller 3 warns the user of thisstate.

With this operation, the user can check the degree of batteryconsumption before he/she uses the electronic device.

In the apparatus disclosed in Jpn. Pat. Appln. KOKAI Publication No.3-253828, a camera battery checking unit includes a battery voltagedetermination control means for operating a battery voltagedetermination means a lapse of a predetermined period of time after ashift from the operation mode to the standby mode.

According to this apparatus, even if a warning is displayed in theoperation mode, when the battery is restored after a lapse of a certainperiod of time, the warning display is updated and erased in the standbymode. In addition, since long battery check intervals can be set in thestandby mode, unnecessary consumption of power for battery checks can beprevented.

It is, however, not easy to directly apply a battery voltage detectionfunction like the one shown in FIG. 10 to a code reading apparatus foroptically reading a dot code like the one described above andreproducing/outputting the original audio information or the like forthe following reason.

A code reading apparatus of this type consumes a large amount ofcurrent, as described above. In order to save power, therefore, thisapparatus uses a sequence of setting a standby state before scanning andafter the code is scanned and the audio information or the like isreproduced/output.

FIGS. 11A and 11B show the relationship between the operation state ofthe code reading apparatus and changes in battery voltage level.

As shown in FIGS. 11A and 11B, in the standby state, since the load islight, the battery voltage is maintained high. In the scan state,however, since various circuit systems for, e.g., illumination, imagesensing, and signal processing, operate, the load becomes heavy, and thebattery voltage is low. In the audio reproduction state, since only thecircuit system for audio reproduction processing becomes a load, theload is lighter than that in the scan state.

Furthermore, in the scan state, owing to the operation sequence for theabove circuit systems, a large change in current consumptioninstantaneously occurs.

That is, since the load in a code reading apparatus like the presentinvention greatly changes with time as compared with an apparatus likethe camera disclosed in Jpn. Pat. Appln. KOKAI Publication No. 3-253828,the consumption state of the battery cannot be satisfactorily detectedby a method like the one disclosed in this reference.

As described above, in a code reading apparatus of this type, thecurrent consumption changes due to the contents of a sequence ofprocessing, from scanning of a code to reproduction/output of audioinformation or the like, and hence the battery voltage changes in a timeseries manner. Owing to such a special circumstance, an intended objectcannot be achieved by the simple method of detecting a battery voltageupon power-on as shown in FIG. 10 or the method disclosed in Jpn. Pat.Appln. KOKAI Publication No. 3-253828.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in consideration of the abovesituation, and has as its object to provide a power-saving code readingapparatus using a sequence in which the supply voltage of a power supplycircuit system including a battery changes in a time series manner,which apparatus includes an optimal battery voltage detection functioncapable of always detecting the consumption state of a battery voltagewith high precision and giving the user a warning.

In order to achieve the above object, according to the first aspect ofthe present invention, there is provided a code reading apparatuscomprising:

illumination means for illuminating a code on a recording medium, onwhich data about audio information is recorded as an optically readablecode, by repeatedly emitting light at predetermined intervals;

image sensing means for receiving each of light beams reflected by therecording medium including the code illuminated by the illuminationmeans in a read/scan operation for the code, and outputting acorresponding image sensing signal;

signal processing means for decoding the data about the audioinformation by processing the image sensing signal output from the imagesensing means;

reproduction output means for reproducing the audio information on thebasis of the data decoded by the signal processing means and outputtingthe information;

supply voltage detection means for detecting a supply voltage to a powersupply circuit system including a battery used as a power supply of theapparatus;

a power switch for turning on/off the supply voltage to the power supplycircuit system; and

detection timing control means for controlling the supply voltagedetection means to detect the supply voltage at a predetermined timingin image sensing operation performed by the image sensing means at thetime of light emission after the supply voltage to the power supplycircuit system is turned on by the power switch and first light emissionis performed by the illumination means.

This aspect of the present invention corresponds to the first, second,third, and fourth embodiments to be described later.

According to the first aspect of the present invention, in the codereading apparatus, the load of the battery can be set nearly in thesteady state by the first light emission from the illumination meansafter the switch is turned on, and the consumption state of the batterycan be reliably detected. If, for example, an output from a regulator orthe power supply terminal of an IC where a supply voltage in the codereading apparatus, other than the battery voltage, reflects theconsumption state of the battery, the consumption state of the batterycan be reliably detected by monitoring such a supply voltage.

According to the code reading apparatus of the second aspect of thepresent invention, in the code reading apparatus of the first aspect,the image sensing means includes a solid-state image sensing device forstoring signal charge corresponding to the reflected light by setting anexposure interval after unnecessary charge stored in a light-receivingsection is removed, and transferring the stored signal charge from thelight-receiving section to a light-shielding section after the end ofthe exposure interval, thereby performing electronic shutter operation,and the detection timing control means controls the supply voltagedetection means to detect a supply voltage at a predetermined timingwithin a predetermined interval constituted by an interval in which theunnecessary charge is removed, the exposure interval, and an interval inwhich the signal charge is transferred from the light-receiving sectionto the light-shielding section.

This aspect of the present invention corresponds to the first, second,third, and fourth embodiments to be described later.

The second aspect of the present invention is characterized in thatsupply voltage detection is performed in the predetermined interval tofurther ensure the effect of the first aspect.

In the predetermined interval, the load instantaneously becomesheaviest. That is, the supply voltage in the predetermined intervalaccurately reflects the consumption of the battery. By detecting thesupply voltage in this interval, the consumption state of the batterycan be accurately detected.

According to the code reading apparatus of the third aspect of thepresent invention, in the code reading apparatus of the first aspect,the image sensing means includes a solid-state image sensing device forstoring signal charge corresponding to the reflected light by setting anexposure interval after unnecessary charge stored in a light-receivingsection is removed, and transferring the stored signal charge from thelight-receiving section to a light-shielding section after the end ofthe exposure interval, thereby performing electronic shutter operation,and the detection timing control means controls the supply voltagedetection means to detect a supply voltage at a predetermined timingwithin a predetermined interval between the instant at which an imagesensing signal is output from the solid-state image sensing device and anext unnecessary charge removal interval.

This aspect of the present invention corresponds to the first, second,third, and fourth embodiments to be described later.

According to the third aspect of the present invention, supply voltagedetection is performed in the predetermined interval to further ensurethe effect of the first aspect. In the predetermined interval, thesupply voltage gradually changes. Even if, therefore, a voltagedetection timing offset occurs, the difference between detected voltagesdue to the timing offset is small. This allows reliable detection of thesupply voltage.

According to the code reading apparatus of the fourth aspect of thepresent invention, in the code reading apparatuses of the first to thirdaspects, the power supply circuit system including the battery isinhibited from supplying power to a circuit system associated with thereproduction output means in a read interval including the timing atwhich the supply voltage detection means detects a supply voltage.

This aspect of the present invention corresponds to the first, second,third, and fourth embodiments to be described later.

The consumption state of the battery is preferably determined bydetecting the supply voltage in a state wherein the load becomes theheaviest. From this viewpoint, the supply voltage should be detectedwhile all the circuits are energized. In a code reading apparatus ofthis type, however, power supply control is performed not tosimultaneously energize all the circuits in an operation sequence tosave power. For this reason, the code reading apparatus of this aspectis designed to inhibit the power supply circuit system including thebattery from supplying power to the circuit system associated with thereproduction output means. This can prevent unnecessary currentconsumption.

According to the code reading apparatus of the fifth aspect of thepresent invention, in the code reading apparatuses of the first to thirdaspects, the detection timing control means controls the supply voltagedetection means to detect the supply voltage at a predetermined timingbefore first emission is performed by the illumination means after thepower switch is turned on, and the code reading apparatus furthercomprises warning means for generating a warning when a difference orratio between a supply voltage detected by the supply voltage detectionmeans at a predetermined timing before the first emission and a supplyvoltage detected by the supply voltage detection means at apredetermined timing after the first emission exceeds a predeterminedlevel.

This aspect of the present invention corresponds to the third and fourthembodiments to be described later.

In this aspect, voltage detection is performed by the regulator. If,however, the type of battery is determined in advance, the batteryvoltage may be directly monitored.

According to the code reading apparatus of the fifth aspect of thepresent invention, a supply voltage detection means that exhibits greatvariations in detected voltage, e.g., the A/D converter in the systemcontrol section, can be used, and the consumption of the battery can bereliably detected even if the detected voltages vary.

The code reading apparatus of the sixth aspect of the present inventionis characterized in that the detection timing control means controls thesupply voltage detection means to detect the supply voltage at apredetermined timing in image sensing operation performed by the imagesensing means at the time of each of light emission operations after thepower switch is turned on and first light emission is performed by theillumination means, and the warning means generates a warning when adifference or ratio between the supply voltage detected by the supplyvoltage detection means at the predetermined timing before the firstlight emission and an average of the supply voltages detected by thesupply voltage detection means a plurality of number of times exceeds apredetermined level.

This aspect of the present invention corresponds to the fourthembodiment to be described later.

In addition to the effect of the fifth aspect, the sixth aspect of thepresent invention has the effect of reducing variations in detectedvoltage, even if noise is produced or the A/D conversion timing slightlyshifts, by averaging the values detected a plurality of number of timesin the steady state.

This averaging processing may be performed by averaging the valuesdetected a plurality of number of times from the start of scanning oraveraging all the values detected in the scan operation.

According to the code reading apparatus of the seventh aspect of thepresent invention, in the code reading apparatus of the fifth aspect,the detection timing control means controls the supply voltage detectionmeans to detect the supply voltage, a plurality of number of times at ahigh speed, at a predetermined timing before first light emission isperformed by the illumination means after the power switch is turned on,and also controls the supply voltage detection means to detect thesupply voltage, a plurality of number of times at a high speed, at apredetermined timing in image sensing operation performed by the imagesensing means at the time of light emission after the power switch isturned on and the first light emission is performed by the illuminationmeans, and the warning means generates the warning when a difference orratio between an average of the supply voltages detected by the supplyvoltage detection means at the predetermined timing before the firstlight emission and an average of the supply voltages detected by thesupply voltage detection means at the predetermined timing after thefirst light emission exceeds a predetermined level.

This aspect of the present invention corresponds to the seventhembodiment to be described later.

According to the seventh aspect of the present invention, in the fifthaspect, the supply voltage can be detected while the influences ofirregular noise such as power supply switching noise are reduced bydetecting the supply voltage a plurality of number of times at a highspeed, and a warning can be generated with little variation.

According to the code reading apparatus of the eighth aspect of thepresent invention, in the code reading apparatus of the seventh aspect,the supply voltage detection means detects the supply voltage to bedetected the plurality of number of times at the high speed as digitaldata, and calculates the average from the digital data detected theplurality of number of times.

This aspect of the present invention corresponds to the seventhembodiment to be describe later.

According to the eighth aspect of the present invention, in the seventhaspect, the supply voltage is A/D-converted and detected a plurality ofnumber of times at a high speed to obtain a plurality of digital data,and the average of the digital data is calculated. With this operation,a level stabilizing circuit such as a capacitor that is required toobserve the supply voltage as an analog waveform can be omitted, and thenumber of circuit components required to generate a warning can bedecreased.

According to the code reading apparatus of the ninth aspect of thepresent invention, in the code reading apparatus of the fifth aspect,the detection timing control means controls the supply voltage detectionmeans to detect the supply voltage at a predetermined timing in imagesensing operation performed by the image sensing means at the time ofeach of a plurality of light emission operations after the power switchis turned on and first light emission is performed by the illuminationmeans, and the warning means generates a warning when any one ofdifferences or ratios between the supply voltage detected by the supplyvoltage detection means at the predetermined timing before the firstlight emission and the supply voltages detected by the supply voltagedetection means the plurality of number of times exceeds a predeterminedlevel.

This aspect of the present invention corresponds to the eighthembodiment to be described later.

The supply voltage drops in different manners depending on the type ofboosting circuit or regulator. When the supply voltage drops with anegative slope in a read interval, a drop in supply voltage cannot bedetected at the start of the read interval. The code reading apparatusof this aspect is therefore designed to obtain the difference or ratiobetween the supply voltage detected before first light emission and eachof the supply voltages detected a plurality of number of times after thefirst light emission so as to detect the supply voltage in the readinterval as well. With this operation, in addition to the effect of thefifth aspect, the ninth aspect has the effect of reliably generating awarning even if the supply voltage level starts dropping at somemidpoint in the read interval.

According to the code reading apparatus of the 10th aspect of thepresent invention, in the code reading apparatus of the fifth aspect,the detection timing control means controls the supply voltage detectionmeans to detect the supply voltage at a predetermined timing in imagesensing operation performed by the image sensing means at the time ofeach of a plurality of light emission operations after the power switchis turned on and first light emission is performed by the illuminationmeans, and the warning means generates a warning in accordance with thenumber of times or the time during which a difference or ratio, ofdifferences or ratios between the supply voltage detected by the supplyvoltage detection means at the predetermined timing before the firstlight emission and the supply voltages detected by the supply voltagedetection means the plurality of number of times, which exceeds apredetermined level is detected.

This aspect of the present invention corresponds to the ninth embodimentto be described later.

The supply voltage drops in different manners depending on the type ofboosting circuit or regulator. When the supply voltage abruptly dropsstepwise in a read interval, a drop in supply voltage cannot be detectedat the start of the read interval. According to the code readingapparatus of this aspect, therefore, the number of times or the timeduring which the difference or ratio between the supply voltage detectedbefore the first light emission and each of the supply voltages detecteda plurality of number of times after the first emission light exceeds apredetermined level is counted. With this operation, in addition to theeffect of the fifth embodiment, the 10th aspect has the effect ofreliably generating a warning even if the supply voltage abruptly dropsstepwise at some midpoint in the read interval.

According to the code reading apparatus of the 11th aspect of thepresent invention, in the code reading apparatuses of first to thirdaspects, the detection timing control means controls the supply voltagedetection means to detect the supply voltage at a predetermined timingbefore first light emission is performed by the illumination means afterthe power switch is turned on, and the code reading apparatus furthercomprises power supply inhibition means for inhibiting the power supplycircuit system from supplying power to the illumination means and/or theimage sensing means when a difference or ratio between the supplyvoltage detected by the supply voltage detection means at thepredetermined timing before the first light emission and the supplyvoltage detected by the supply voltage detection means at apredetermined timing after the first light emission exceeds apredetermined level.

This aspect of the present invention corresponds to the fifth embodimentto be described later.

According to the 11th aspect of the present invention, when the supplyvoltage extremely drops, the system control section detects the levelbefore the occurrence of an operation error, and inhibits supply ofpower to the illumination means and the image sensing means which areheavy loads. This suppresses further consumption of the battery and canprevent an operation error in the system control section.

According to the code reading apparatus of the 12th aspect of thepresent invention, in the code reading apparatus of the 11th aspect, thedetection timing control means controls the supply voltage detectionmeans to detect the supply voltage at a predetermined timing in imagesensing operation performed by the image sensing means at the time ofeach of light emission operations after the power switch is turned onand first light emission is performed by the illumination means, and thepower supply inhibition means inhibits the supply of power when adifference or ratio between the supply voltage detected by the supplyvoltage detection means at the predetermined timing before the firstlight emission and an average of the supply voltages detected by thesupply voltage detection means a plurality of number of times exceeds apredetermined level.

This aspect of the present invention corresponds to the sixth embodimentto be described later.

According to the 12th aspect of the present invention, in the firstaspect, by averaging the values detected a plurality of number of timesin the steady state, variations in detected value can be reduced, andinhibition of power supply can be reliably performed when noise isproduced or the A/D conversion timing slightly shifts.

This averaging processing may be performed by averaging the valuesdetected a plurality of number of times from the start of scanning oraveraging all the values detected during scanning.

According to the code reading apparatus of the 13th aspect of thepresent invention, in the code reading apparatus of the 11th aspect, thedetection timing control means controls the supply voltage detectionmeans to detect the supply voltage, a plurality of number of times at ahigh speed, at a predetermined timing before first light emission isperformed by the illumination means after the power switch is turned on,and also controls the supply voltage detection means to detect thesupply voltage, a plurality of number of times at a high speed, at apredetermined timing in an image sensing operation performed by theimage sensing means at the time of light emission after the power switchis turned on and the first light emission is performed by theillumination means, and the power supply inhibition means inhibits thesupply of power when a difference or ratio between an average of thesupply voltages detected by the supply voltage detection means at thepredetermined timing before the first light emission and an average ofthe supply voltages detected by the supply voltage detection means atthe predetermined timing after the first light emission exceeds apredetermined level.

This aspect of the present invention corresponds to the seventhembodiment to be described later.

In addition to the effect of the 11th aspect, the 13th aspect of thepresent invention has the effect of detecting a supply voltage whilereducing the influences of irregular noise such as power supplyswitching noise by detecting the supply voltage a plurality of number oftimes at a high speed and averaging the detected voltages, therebyinhibiting power supply with little variations.

According to the code reading apparatus of the 14th aspect of thepresent invention, in the code reading apparatus of the 13th aspect, thesupply voltage detection means detects the supply voltage to be detectedthe plurality of number of times at the high speed as digital data, andcalculates the average from the digital data detected the plurality ofnumber of times.

This aspect of the present invention corresponds to the seventh aspectto be described later.

According to the 14th aspect of the present invention, in the 13thaspect, the supply voltage is A/D-converted and detected a plurality ofnumber of times to obtain a plurality of digital data, and the averageof the digital data is calculated. With this operation, a levelstabilizing circuit such as a capacitor that is required to observe thesupply voltage as an analog waveform can be omitted, and the number ofcircuit components required to inhibit power supply can be decreased.

According to the code reading apparatus of the 15th aspect of thepresent invention, in the code reading apparatus of the 11th aspect, thedetection timing control means controls the supply voltage detectionmeans to detect the supply voltage at a predetermined timing in imagesensing operation performed by the image sensing means at the time ofeach of a plurality of light emission operations after the power switchis turned on and first light emission is performed by the illuminationmeans, and the power supply inhibition means inhibits the supply ofpower when any one of differences or ratios between the supply voltagedetected by the supply voltage detection means at the predeterminedtiming before the first light emission and the supply voltages detectedby the supply voltage detection means the plurality of number of timesexceeds a predetermined level.

This aspect of the present invention corresponds to the eighthembodiment to be described later.

The supply voltage drops in different manners depending on the type ofboosting circuit or regulator. When the supply voltage drops with anegative slope in a read interval, a drop in supply voltage cannot bedetected at the start of the read interval. The code reading apparatusof this aspect is therefore designed to obtain the difference or ratiobetween the supply voltage detected before first light emission and eachof the supply voltages detected a plurality of number of times after thefirst light emission so as to detect the supply voltage in the readinterval as well. With this operation, in addition to the effect of the11th aspect, the 15th aspect has the effect of reliably inhibiting powersupply even if the supply voltage level starts dropping at some midpointin the read interval.

According to the code reading apparatus of the 16th aspect of thepresent invention, in the code reading apparatus of the 11th aspect, thedetection timing control means controls the supply voltage detectionmeans to detect the supply voltage at a predetermined timing in imagesensing operation performed by the image sensing means at the time ofeach of a plurality of light emission operations after the power switchis turned on and first light emission is performed by the illuminationmeans, and the power supply inhibition means inhibits the supply ofpower in accordance with the number of times or the time during which adifference or ratio, of differences or ratios between the supply voltagedetected by the supply voltage detection means at the predeterminedtiming before the first light emission and the supply voltages detectedby the supply voltage detection means the plurality of number of times,which exceeds a predetermined level is detected.

This aspect of the present invention corresponds to the ninth embodimentto be described later.

The supply voltage drops in different manners depending on the type ofboosting circuit or regulator. When the supply voltage abruptly dropsstepwise in a read interval, a drop in supply voltage cannot be detectedat the start of the read interval. According to the code readingapparatus of this aspect, therefore, the number of times or the timeduring which the difference or ratio between the supply voltage detectedbefore the first light emission and each of the supply voltages detecteda plurality of number of times after the first emission light exceeds apredetermined level is counted. With this operation, in addition to theeffect of the 11th embodiment, the 16th aspect has the effect ofreliably inhibiting power supply even if the supply voltage abruptlydrops stepwise at some midpoint in the read interval.

According to the 17th aspect of the present invention, there is provideda code reading method comprising the steps of:

illuminating a code on a recording medium, on which data about audioinformation is recorded as an optically readable code, by repeatedlyemitting light at predetermined intervals;

receiving each of light beams reflected by the recording mediumincluding the code in a read/scan operation for the code, and outputtinga corresponding image sensing signal;

decoding the data about the audio information by processing the imagesensing signal;

reproducing the audio information on the basis of the data andoutputting the information;

detecting a supply voltage to a power supply circuit system including abattery used as a power supply;

turning on/off the supply voltage to the power supply circuit system;and

controlling to detect the supply voltage at a predetermined timing inimage sensing operation in the step of outputting the image sensingsignal at the time of light emission after the supply voltage to thepower supply circuit system is turned on and first light emission isperformed in the step of illuminating the code.

According to the 17th aspect of the present invention, the same functionand effect as those of the code reading apparatus of the first aspectcan be obtained.

According to the code reading method of the 18th aspect of the presentinvention, in the code reading method of the 17th aspect, the step ofoutputting the image sensing signal includes the step of causing asolid-state image sensing device to store signal charge corresponding tothe reflected light by setting an exposure interval after unnecessarycharge stored in a light-receiving section is removed, and transfer thestored signal charge from the light-receiving section to alight-shielding section, thereby performing electronic shutteroperation, and the step of controlling includes the step of controllingto detect the supply voltage at a predetermined timing within apredetermined interval constituted by an interval in which theunnecessary charge is removed, the exposure interval, and an interval inwhich the signal charge is transferred from the light-receiving sectionto the light-shielding section.

According to the 18th aspect of the present invention, the same functionand effect as those of the code reading apparatus of the second aspectcan be obtained.

According to the code reading method of the 19th aspect of the presentinvention, in the code reading method of the 17th aspect, the step ofoutputting the image sensing signal includes the step of causing asolid-state image sensing device to store signal charge corresponding tothe reflected light by setting an exposure interval after unnecessarycharge stored in a light-receiving section is removed, and transfer thestored signal charge from the light-receiving section to alight-shielding section after the end of the exposure interval, therebyperforming electronic shutter operation, and the step of controllingincludes the step of controlling to detect the supply voltage at apredetermined timing within a predetermined interval between the instantat which an image sensing signal is output from the solid-state imagesensing device and a next unnecessary charge removal interval.

According to the 19th aspect of the present invention, the same functionand effect as those of the code reading apparatus of the third aspectcan be obtained.

According to the code reading method of the 20th aspect of the presentinvention, in the code reading methods of the 17th, 18th, and 19thaspects, the code reading method is characterized by further comprisingthe step of inhibiting the power supply circuit including the batteryfrom supplying power to a circuit system associated with reproductionand output of the audio information in the step of outputting the imagesensing signal during a read/scan interval for the code, which includesthe timing at which the supply voltage is detected in the step ofdetecting the supply voltage.

According to the 20th aspect of the present invention, the same functionand effect as those of the code reading apparatus of the fourth aspectcan be obtained.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention and, together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a block diagram showing the arrangement of a code readingapparatus according to the first embodiment of the present invention;

FIGS. 2A to 2G are timing charts showing changes in supply voltage inthe code reading apparatus according to the first embodiment of thepresent invention;

FIGS. 3A and 3B are views showing the structure of a CCD in the codereading apparatus according to the first embodiment of the presentinvention;

FIG. 4 is a block diagram showing the arrangement of a code readingapparatus according to the second embodiment of the present invention;

FIG. 5 is a block diagram showing the arrangement of a code readingapparatus according to the third embodiment of the present invention;

FIGS. 6A and 6B are timing charts showing the voltage detection timingsof a code reading apparatus according to the fourth embodiment of thepresent invention;

FIG. 7 is a flow chart showing the flow of the operation of a codereading apparatus according to the seventh embodiment of the presentinvention;

FIGS. 8A to 8C are timing charts showing the relationship between thesupply voltage, the emission pulse timing, and the supply voltagedetection timing in the code reading apparatuses according to the eighthand ninth embodiments of the present invention;

FIGS. 9A and 9B are view showing the arrangement of a dot code accordingto the prior art;

FIG. 10 is a block diagram showing the arrangement of a battery voltagedetection circuit in the conventional apparatus; and

FIGS. 11A and 11B are views showing an operation sequence in a codereading apparatus according to the prior art.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the presently preferredembodiments of the invention as illustrated in the accompanyingdrawings, in which like reference characters designate like orcorresponding parts throughout the several drawings.

Embodiments of the present invention will be described below withreference to the views of the accompanying drawing.

(First Embodiment)

FIG. 1 is a block diagram showing a code reading apparatus according tothe first embodiment of the present invention.

The code reading apparatus of the first embodiment is mainly made up ofan image sensing section 21, a signal processing section 22, an audiooutput section 23, and a power supply section 24.

More specifically, this embodiment has the following arrangement.

After a power switch 14 in the power supply section 24 is turned on,boosting circuits 9a and 9b operate upon reception of power from abattery 1. As a result, a supply voltage is supplied to a regulator 10,the signal processing section 22, and a regulator 11.

Upon reception of a signal as a scan command from an operating section(not shown), a system controller 3 turns on the regulator 10 to supplypower to the image sensing section 21. After the image sensing section21 is energized, the system controller 3 cancels the standby state of animage sensing driving circuit 4 to drive a solid-state image sensingdevice 5 as a typical example of an interline or frame transfer CCD.

An illumination power supply circuit 16 generates the supply voltage foran illumination element 8 by boosting the voltage applied from theregulator 10 to the image sensing section 21.

The boosting operation in this case may be performed by using a generalcharge pump circuit.

The system controller 3 drives the solid-state image sensing device 5and the illumination element 8 at the same time.

This illumination element 8 performs so-called pulse emissionillumination, i.e., emitting light at predetermined intervals toilluminate the code printed/recorded on a recording medium.

By instantaneously emitting illumination light in the form of pulses inthis manner, an image that has good contrast and is free from image blurcan be obtained even if the code reading apparatus is manually scanned.

The solid-state image sensing device 5 sequentially outputs dot codeimage data, obtained with repeatedly emitted pulse illumination light,to an A/D (Analog/Digital) converter 6 in units of frames.

The A/D converter 6 sequentially converts the dot code image data into adigital signal in units of frames, and outputs the digital signal to asignal processing circuit 7 for performing binarization, demodulation,de-interleaving, error correction, and the like.

The data processed/decoded by the signal processing circuit 7 is storedin a memory (not shown) and is sequentially decompressed and convertedinto audio data.

Since this conversion processing is described in detail in Jpn. Pat.Appln. KOKAI Publication No. 6-231466 (EP No. 0,670,555A1), adescription thereof will be omitted.

In this embodiment, reproduction is started after scanning is complete.

The system controller 3 turns off the power to the image sensing section21 and turns on the regulator 11 to supply power to the audio outputsection 23.

The audio output section 23 receives the digital audio output from thesystem controller 3 and converts it into an analog audio signal througha D/A (Digital/Analog) converter 12. The audio output section 23 thensupplies this analog audio signal to an audio output unit 13 such as anearphone.

The supply voltage of the battery 1 is detected by voltage detectors 2aand 2b.

More specifically, the voltage detector 2a detects a voltage level atwhich a warning should be given to the user. The voltage detector 2bdetects a voltage level at which the circuit is stopped to prevent anoperation error.

The outputs from these voltage detectors 2a and 2b are input to thesystem controller 3.

Upon reception of the output from the voltage detector 2a, the systemcontroller 3 drives a warning section 15 to generate a warning by asound or display. Upon reception of the output from the voltage detector2b, the system controller 3 operates to maintain a standby state even ifit receives a scan command.

In this case, the timing at which the system controller 3 receives theoutputs from the voltage detectors 2a and 2b is important.

As shown in FIG. 11 described above, the system controller 3 checksoutputs from the voltage detectors 2a and 2b during scanning so as tomaximize the load in the scanning state.

A rising load and steady load will be described in detail with referenceto FIGS. 2A to 2G which show detailed timing charts.

FIG. 2A shows the power-on state of the image sensing section 21. Hlevel indicates the state in which the power to the image sensingsection 21 is turned on, i.e., the scanning state.

FIGS. 2B to 2G respectively show the states of a vertical blankingpulse, an illumination pulse, vertical charge transfer, illuminationpower, image sensing device power, and battery power.

In this case, since the load state is unstable during a power riseperiod, it is inappropriate for detection of a supply voltage. Hence, asupply voltage is detected after a steady load state is set.

In the illumination circuit system of the image sensing section 21, inparticular, a large current flows, although it flows for a short periodof time, and the supply voltage is high. The load on this system istherefore heavy.

Furthermore, as shown a dot detection start frame in FIG. 2B, a processfor detecting a dot from the image of the dot code is started, afterilluminating a plurality of number times of illumination pulses.

At the vertical charge transfer timing in FIG. 2D, the vertical shiftregister of the solid-state image sensing device discharges unnecessarycharge to electronic shutter operation before illumination emission.Thereafter, the load is increased to transfer signal charge.

That is, the timing before and after illumination emission is the timingat which the load is maximized.

FIG. 2F shows the supply voltage to the image sensing device. Since theload increases at the time of unnecessary charge removal and the time ofsignal charge transfer as described with reference to FIG. 2D, thesupply voltage to this image sensing device dips at these times.

Changes in current consumption due to the operation of the CCD, i.e.,changes in supply voltage to the CCD, will be described below withreference to FIGS. 3A and 3B.

Currently, as solid-state image sensing devices, an interline transferCCD and a frame transfer CCD are generally used, as shown in FIGS. 3Aand 3B.

The interline transfer CCD shown in FIG. 3A is of a forward dischargetype, and the frame transfer CCD shown in FIG. 3B is of the reversecharge type.

Since the operations of these CCDs are described in detail in variousliteratures, a detailed description thereof will be omitted.

Since the frame transfer CCD shown in FIG. 3B has a storage sectionhaving the same capacity as that of a light-receiving section, thecurrent consumption of this CCD tends to be larger than that of theinterline transfer CCD shown in FIG. 3A which has the same size as thatof the CCD in FIG. 3B.

In the frame transfer CCD shown in FIG. 3B, after the unnecessary chargestored in the light-receiving section is removed, an exposure intervalis set to store signal charge corresponding to received light, and thestored signal charge is transferred from the light-receiving section tothe light-shielding section after the end of the exposure interval,thereby performing electronic shutter operation. The current consumptionbecomes largest at the time of unnecessary charge removal and the timeof signal charge transfer. The current consumptions at these times arealmost equal to each other.

In the embodiments of the present invention, the frame transfer CCDshown in FIG. 3B is used, and the supply voltage to the CCD changes asshown in FIG. 2F with time-series changes in current consumption.

FIG. 2E shows the supply voltage to the illumination circuit. The supplyvoltage to this illumination circuit is higher than the power to theimage sensing section 21, and is generated by the illumination powersupply circuit 16.

Assume that the current capacity of the illumination power supplycircuit 16 is small. In this case, since the load at the time of lightemission is heavy, the level of the power changes with variations inload, as indicated by the waveform shown in FIG. 2E.

In addition, as shown in FIG. 2C, the illumination circuit is kept offfor a 1-frame period (H level indicates illumination lighting) afterpower is supplied to the image sensing section.

This operation is performed to quickly start up the illumination power.Since the level of the illumination power at the timing of the firstillumination pulse is higher than that in a steady load state, the powerat this time cannot be called a steady-stage load. At the timing of thesecond illumination pulse, however, the illumination power substantiallybecomes a steady load. If, therefore, a supply voltage is detected atthis timing, accurate voltage detection for a steady load state can beperformed.

FIG. 2G shows the battery voltage and the detection timings. Asdescribed above, this battery voltage changes as shown in FIG. 2G owingto the influences of illumination power and image sensing device power,in particular.

Referring to FIGS. 2A to 2F, two voltage detection timings, namelyvoltage detection timings 1 and 2, are set. In actual operation,however, one voltage detection timing will suffice.

The reason why voltage detection timing 2 is set at the timing at whichthe battery voltage becomes lowest is that the voltage varies greatlywhen the load is maximized, and this reflects the consumption state ofthe battery 1 most.

Detection at this timing is performed on the precondition that thetimings at which the system controller 3 receives outputs from thevoltage detectors 2a and 2b do not shift.

The reason why voltage detection timing 1 is set at the timing at whichthe battery voltage is stable is that since the voltage greatly variesat the time of the maximum load, even a slight difference between thetimings at which the system controller 3 receives outputs from thevoltage detectors 2a and 2b makes it impossible to perform accuratevoltage detection.

Both detection timing 1 and detection timing 2 allow an improvement inthe voltage detection precision for the battery 1. Obviously, both thetimings can be used.

With the use of this embodiment, even in a system in which the loadstate changes, the voltage of a battery can be reliably detected, andhence the consumption state of the battery can be detected.

Although the voltage detectors 2a and 2b are used to monitor the batteryvoltage, the A/D converter incorporated in the system controller 3 maybe used as in the third embodiment to be described later.

(Second Embodiment)

FIG. 4 shows a code reading apparatus according to the second embodimentof the present invention.

This embodiment has the following arrangement. A description of portionsidentical to those of the first embodiment will be omitted.

In the second embodiment, the input terminals of voltage detectors 2aand 2b are connected to the output terminal of a regulator 10 to monitora voltage after stabilization instead of the voltage of a battery 1.However, the detection timing is set in the same manner as in the firstembodiment.

The manner in which a battery is consumed, i.e., a change in outputvoltage with time, depends on the type of battery.

In the case of a dry battery, for example, the voltage gradually drops.The voltage of a Ni--Cd battery, however, the voltage becomes constantat almost 1.2V, and abruptly drops when the battery is consumed greatly.

That is, different types of batteries differ in their manners ofconsumption and amounts of current that can be consumed even if thebattery output voltages are the same. It is an object of this embodimentto reliably detect even the consumptions of different types ofbatteries.

When a battery is consumed, no current can be supplied. Obviously, ifthe output current from the battery reduces, and a load cannot besatisfactorily driven, the amount of current supplied to each circuitdecreases.

The regulator 10 generally incorporates a reference voltage source. If anecessary amount of current is not supplied from the battery to theregulator 10, the output voltage from the regulator 10 also drops.Therefore, the output voltage from the regulator 10 sufficientlyreflects the consumption of the battery.

As described above, a decrease in the output of the regulator 10indicates a decrease in current supplied from the battery, and reflectsthe supply current state regardless of the type of battery.

According to this embodiment, the consumption state of a battery can bedetected regardless of the type of battery, and hence a warning againstbattery consumption can be reliably made even if various types ofbatteries are used.

In addition, if the code reading apparatus incorporates a portion whosevoltage changes as a battery is consumed, the same effect as describedabove can be obtained by monitoring the output of the portion.

(Third Embodiment)

FIG. 5 shows a code reading apparatus according to the third embodimentof the present invention.

This embodiment has the following arrangements. A description ofportions identical to those in the first and second embodiments will beomitted.

In the third embodiment, to decrease the cost of the circuitarrangement, the voltage detectors 2a and 2b are omitted, and ananalog/digital converter (to be abbreviated as an A/D converterhereinafter) 17 incorporated in a system controller 3 is used to detecta supply voltage.

In this circuit arrangement, an output from a regulator 10 is directlyinput to the system controller 3.

When the output from the regulator 10 is higher than the supply voltage,the output is voltage-divided, and the resultant voltage is input to thesystem controller 3.

In this case, a problem is posed in terms of voltage detectionprecision. Although the detection precision of a commercially availablevoltage detector varies 2 to 3%, it is difficult to obtain the sameprecision by using the A/D converter 17 in consideration of theprecision of the peripheral circuits such as a reference voltagecircuit.

Although the detection precision can be improved by inputting an outputfrom a high-precision voltage generator as an A/D reference to thedetector, an inexpensive circuit arrangement cannot be realized.

If an A/D reference is resistance-divided from the power supply to beinput to the detector, the detected battery consumption in each productvaries due to variations in supply voltage and dividing resistance.

In order to solve the above problem, the supply voltage immediate afterthe power is turned on is compared with the supply voltage duringoperation.

FIGS. 6A and 6B show detection timings. More specifically, at timing (a)at which the supply voltage is stabilized after power-on, and whichcorresponds to a time point before first illumination emission, anoutput from the regulator 10 is supplied to the A/D converter 17, and adigitally converted battery voltage value is stored in a memory (notshown) to detect a battery voltage.

Subsequently, the supply voltage at timing (b) in a steady load state isdetected in the same manner as described above, and a digitallyconverted battery voltage value is stored in the memory (not shown).

The system controller 3 obtains the difference between the detectedvoltage at timing (a) and the detected voltage at timing (b), anddetermines the consumption of the battery 1 on the basis of thedifference. When the determined value exceeds a predetermined level, thesystem controller 3 generates a warning.

In this case, the system controller 3 may determine the batteryconsumption by obtaining the ratio between the detected voltages insteadof the difference. If, for example, the detected voltage at timing (b)exceeds 80% of the detected voltage at timing (a), the system controller3 determines that the battery 1 is exhausted.

Note that timing (2) may be set at either voltage detection timing 1 orvoltage detection timing 2 in the first embodiment.

With the above arrangement, no expensive voltage detector demanding areference voltage is required, and hence power detection can be realizedat low cost.

In this embodiment, an output from the regulator 10 is detected. Evenif, however, the voltage of the battery 1 is directly detected, the sameeffect as described above can be obtained.

(Fourth Embodiment)

A code reading apparatus of the fourth embodiment has the same circuitarrangement as that of the third embodiment in FIG. 5, and hence adescription thereof will be omitted.

In the fourth embodiment, the supply voltage at timing (b) in FIG. 6 isdetected a plurality of number of times, and the average of the detectedvalues is calculated.

Since the supply voltage at timing (b) is detected during the operationof the circuit, the supply voltage contains irregular noise such asripples. For this reason, supply voltage detection is performed aplurality of number of times, and the detected values are averaged toreduce irregular noise components.

By comparing the averaged supply voltage at timing (b) with the supplyvoltage at timing (a), the same effect as that of the third embodimentcan be obtained. In addition, a voltage having no irregular noise can bedetected.

(Fifth Embodiment)

A code reading apparatus of the fifth embodiment has the same circuitarrangement as that of the third embodiment in FIG. 5, and hence adescription thereof will be omitted.

In the fifth embodiment, the ratio between the voltages detected attiming (a) and timing (b) in FIG. 6 is calculated. When the calculatedvalue exceeds a predetermined level, the system controller 3 controls toset a regulator 10 in a standby state through a control line 25, therebyinhibiting the supply of power to an image sensing section 21.

In the code reading apparatuses of the first to fourth embodiments, adrop in supply voltage with consumption of the battery 1 is detected togenerate a warning.

If, however, the user of the code reading apparatus neglects the warningand keeps using the apparatus, the supply voltage drops further. As aresult, the operation of the image sensing section 21 cannot beguaranteed.

More specifically, since the image sensing section 21 drives asolid-state image sensing device 5 such as a CCD and turns on anillumination element 8 such as an LED, the image sensing section 21consumes a large amount of current. In addition, this code readingapparatus uses boosting circuits 9a and 9b for boosting a batteryvoltage because the apparatus uses a high voltage of about 20V as asupply voltage. These boosting circuits 9a and 9b also consume a largeamount of current.

If the battery 1 is exhausted, the internal resistance of the battery 1increases, and a current necessary for the normal operation of the imagesensing section 21 cannot be extracted. This makes it impossible to reada code.

If the user keeps using this apparatus in this state, the load on thebattery 1 increases, and the battery is quickly exhausted.

As a result, the operations of the system controller 3 that uses a lowvoltage of about 3V and a warning section 15 cannot be guaranteed. Thismay lead to inability to give a warning and an operation error in thesystem controller 3.

According to the code reading apparatus of this embodiment, when a dropin battery voltage is detected, the system controller 3 controls tomaintain the regulator 10 in a standby state so as to inhibit the supplyof power to the image sensing section 21. In addition to the effects ofthe first and second embodiments, therefore, this embodiment has theeffect of preventing a drop in supply voltage by suppressing abruptconsumption of the battery 1, and preventing an operation error in thesystem controller.

In this embodiment, the system controller 3 controls to stop theoperation of the regulator 10. If, however, the system controller 3controls to stop the operations of the boosting circuits 9a and 9b, thesame effect as described above can be obtained.

In addition, the difference between the voltages detected at timing (a)and timing (b) may be calculated instead of the ratio.

(Sixth Embodiment)

A code reading apparatus of the sixth embodiment has the same circuitarrangement as that of the third embodiment in FIG. 5, and hence adescription thereof will be omitted.

In the sixth embodiment, the supply voltage at timing (b) in FIG. 6 isdetected a plurality of number of times, and the average of the detectedvalues is calculated. In addition, the ratio between the supply voltagedetected at timing (a) and the average of the supply voltages detectedat timing (b) a plurality of number of times is calculated. When theratio exceeds a predetermined level, a system controller 3 controls toset a regulator 10 in a standby state through a control line 25, therebyinhibiting the supply of power to an image sensing section 21.

Since the supply voltage at timing (b) is detected during the operationof the circuit, the supply voltage contains irregular noise such asripples. For this reason, the detected values are averaged to reduce theinfluences of irregular noise components.

The averaged supply voltage at timing (b) is compared with the supplyvoltage at timing (a), and the supply of power is inhibited on the basisof the comparison result, thereby obtaining the same effect as that ofthe fifth embodiment. In addition, inhibition of power supply can beperformed while the influences of irregular noise components arereduced.

Note that the difference between the voltage detected at timing (a) andthe average of the supply voltages detected at timing (b) a plurality ofnumber of times may be calculated instead of the ratio.

(Seventh Embodiment)

A code reading apparatus of the seventh embodiment has the same circuitarrangement as that of the third embodiment in FIG. 5, and hence adescription thereof will be omitted.

The flow of operation of the code reading apparatus of the seventhembodiment will be described with reference to the flow chart of FIG. 7.

After an illumination power supply circuit 16 is started up by a systemcontroller 3 (step S1), the supply voltage level at timing (a) in FIG. 6(before an illumination element 8 is actually turned on) isA/D-converted at a high speed, and a plurality of digital data aredetected (step S3).

The system controller 3 calculates the average of the plurality ofdigital data (step S5).

The system controller 3 then turns on the illumination element for thefirst time (step S7), and A/D-converts the supply voltage level attiming (b) in FIG. 6 at a high speed. The system controller 3 thendetects a plurality of digital data again (step S9).

The system controller 3 calculates the average of the plurality ofdigital data detected in step S9 (step S11).

The system controller 3 compares the average of the digital datadetected at timing (a) a plurality of number of times with the averageof the digital data detected at timing (b) a plurality of number oftimes (step S13). If the ratio of these values exceeds a predeterminedlevel, read operation is started (step S15). If the ratio is equal to orlower than the predetermined level, a warning is generated (step S17).

As in the previous embodiments, in this embodiment, the differencebetween the voltage detected at timing (a) and the average of the supplyvoltages detected at timing (b) a plurality of number of times may becalculated instead of the ratio.

A supply voltage contains irregular noise such as switching noise. Thiscauses variations in detected voltage. According to the code readingapparatus of this embodiment, however, since the supply voltage isdetected a plurality of number of times at a high speed, and thedetected values are averaged, the effect of performing supply voltagedetection free from the influences of irregular noise components such asswitching noise in power can be obtained in addition to the effect ofthe third embodiment.

In addition, since the supply voltage is detected as a digital value aplurality of number of times, and the detected values are averaged, thisapparatus need not use a smoothing capacitor for smoothing an input tothe detection circuit, which is required to stabilize a detected voltageas an analog value. This allows reductions in the number of parts andcost.

Note that "high speed" in the present invention indicates that the timerequired to obtain one average supply voltage is short, and is aboutseveral 100 μs to several ms in numerical value. This time is determinedby the speed of A/D conversion, the time required for averagingprocessing, and the like.

In general, it takes several μs to A/D-convert one supply voltage leveldata into digital data. Assume that it takes 5 μs for this A/Dconversion. In this case, if 10 digital data are to be averaged toobtain a supply voltage, one sample can be detected within about 50 μs.

In practice, however, the sample/hold time required to temporarily fixan analog voltage value and the time required for software processingfor averaging are added to the above time, it takes several 100 μs toseveral ms to obtain one sample.

The code reading apparatus of this embodiment generates a warning upondetection of a drop in supply voltage. When the averages of the supplyvoltages detected at timing (a) and timing (b) in FIG. 6 a plurality ofnumber of times, and the difference or ratio therebetween exceeds apredetermined level, the system controller 3 stops the operation of aregulator 10 through a control line 25, thereby obtaining the sameeffect as that of the fifth embodiment. In addition, this apparatus caninhibit power supply by accurately detecting a supply voltage withlittle influences of noise using a circuit with a decreased number ofparts.

(Eighth Embodiment)

A code reading apparatus of the eighth embodiment has the same circuitarrangement as that of third embodiment in FIG. 5, and hence adescription thereof will be omitted.

In the code reading apparatus of the eighth embodiment, the supplyvoltage at timing (0) before generation of an emission pulse in FIG. 8Cis detected first, and then supply voltage detection is performed aplurality of number of times in synchronism with the emission pulse, asindicated by timing (1), timing (2), . . . The ratio between the voltageat timing (0) and the voltage at each of the subsequent timings iscalculated. If any one of these ratios exceeds a predetermined level, awarning is generated.

The manner in which the supply voltage drops varies depending on thetypes of boosting circuits 9a and 9b and regulator 10. In some case, thesupply voltage drops with a negative slope in a read interval, asindicated by supply voltage waveform 1 in FIG. 8A.

Since the supply voltage scarcely drops in the first period of a readinterval, a drop in supply voltage cannot be detected by comparing thesupply voltage at timing (0) before first light emission with the supplyvoltage at timing (1) after first light emission (timing (b) in FIG. 6).

According to this embodiment, a warning can be reliably generated bydetecting a drop in supply voltage even in a case wherein the supplyvoltage gradually drops in the second half of a read interval, in whicha warning cannot be generated in the third embodiment. Morespecifically, in the eighth embodiment, a drop in supply voltage isdetected in a read interval by detecting the supply voltages at timing(1), timing (2), . . . throughout the read interval, and calculating theratio between the supply voltage at each timing and the supply voltageat timing (0), thereby reliably generating a warning.

In this case, the ratio between the supply voltage before first lightemission and the supply voltage at each of a plurality of timings afterlight emission is calculated. However, the same effect as describedabove can be obtained by calculating the differences between thesevoltages.

The code reading apparatus of this embodiment generates a warning upondetection of a drop in supply voltage. However, this apparatus maycompare the supply voltage before first light emission and the supplyvoltage at a given timing after first light emission, and a systemcontroller 3 may stop the operation of the regulator 10 through acontrol line 25 when the ratio or difference between the supply voltagesexceed a predetermined level. With this operation, the apparatus canreliably detect a drop in supply voltage and inhibit power supply evenin a case wherein the supply voltage gradually drops in the secondperiod of a read interval, in which the code reading apparatus of thefifth embodiment cannot inhibit power supply.

(Ninth Embodiment)

A code reading apparatus of the ninth embodiment has the same circuitarrangement as that of third embodiment in FIG. 5, and hence adescription thereof will be omitted.

The code reading apparatus of the ninth embodiment perform supplyvoltage detection a plurality of number of times, as indicated by timing(1), timing (2), . . . in FIG. 8C, and calculates the difference orratio between each detected voltage and the supply voltage at timing(0). This apparatus then counts the overall number of times of detectionand the number of times the difference or ratio between the supplyvoltages has exceeded a predetermined level by using the counter (notshown) incorporated in a system controller 3. When the ratio between theoverall number of times of detection and the number of times thedifference or ratio between the supply voltages has exceeded thepredetermined level exceeds a predetermined level, the apparatusgenerates a warning.

The manner in which the supply voltage drops varies depending on thetypes of boosting circuits 9a and 9b and regulator 10. In some case, thesupply voltage abruptly drops stepwise in a read interval, as indicatedby supply voltage waveform 2 in FIG. 8B.

In this case, since the supply voltage scarcely drops in the firstperiod of the read interval, a drop in supply voltage cannot bedetected, and no warning can be generated by comparing the supplyvoltage timing (0) before first light emission with timing (1) afterfirst light emission (timing (b) in FIG. 6).

Referring to FIG. 8B, "M" of supply voltage waveform 2 indicates thenumber of times of supply voltage detection in an interval during whichthe supply voltage is in a steady state, and "N" indicates the number oftimes of supply voltage detection in an interval during which the supplyvoltage drops.

In this state, the code reading apparatus can properly read the codeuntil Mth detection of the supply voltage, but cannot read the codeafter Mth detection of the supply voltage.

That is, M/(M+N), which is the ratio of the above numbers of times,indicates the ratio at which a read error has occurred in the readinterval and the degree to which the read operation is effective.

If this value exceeds a predetermined level, a warning is generated.With this operation, this apparatus can reliably generate a warning evenin a case wherein the supply voltage abruptly changes stepwise in a readinterval, as indicated by supply voltage waveform 2, in which a warningcannot be generated according to the third embodiment.

In this case, M/(M+N), i.e., the ratio between the numbers of times ofdetection, is obtained. However, the number of times N may be detectedas the difference between (the overall number of times of detection) and(the number of times of detection in a state wherein the supply voltagedrops).

In this embodiment, the overall number of times of detection and thenumber of times of detection in a state wherein the supply voltage dropsto a level lower than the predetermined level are counted by thecounter. However, the same effect as described above can be obtained bymeasuring the corresponding times with a timer.

More specifically, a timer (not shown) is set in the system controller 3to measure the time during which the code is properly read and the timeduring which the code cannot be read.

The timer is reset to start measuring the time at the timing of power-onin FIG. 8B. When the supply voltage drops to exceed a predeterminedlevel, the timer is reset again. At the same time, the time during whichthe code is properly read is stored in a memory (not shown).

In addition, the timer is reset again at the timing of power-off, and atthe same time, the time during which the code cannot be read is storedin the memory.

The system controller 3 compares with the time measured until the supplyvoltage exceeds the predetermined level with the time between theinstant at which the supply voltage exceeds the predetermined level andthe instant at which the power is turned off, thereby generating awarning.

In this embodiment, when a drop in supply voltage is detected, a warningis generated. However, the embodiment may be designed such that thenumber of times of detection in a state wherein the supply voltage is ina steady state is compared with the number of times of detection in astate wherein the supply voltage drops, and the system controller 3stops the operation of the regulator 10 through the control line 25 whenthe difference or ratio between the numbers of times of detectionexceeds a given level. With this operation, this embodiment can reliablyinhibit power supply even in a state wherein a drop in supply voltagecannot be detected and power supply cannot be inhibited in the fifthembodiment, i.e., a case wherein the supply voltage abruptly dropsstepwise in a read interval.

According to the code reading apparatus of the present invention, theconsumption state of a battery can always be detected with highprecision, and a warning can be given to the user.

As has been described in detail above, according to the presentinvention, there is provided a power-saving code reading apparatus usinga sequence in which the supply voltage of a power supply circuit systemincluding a battery changes in a time series manner, which apparatusincludes an optimal battery voltage detection function capable of alwaysdetecting the consumption state of a battery voltage with high precisionand giving the user a warning.

Additional embodiments of the present invention will be apparent tothose skilled in the art from consideration of the specification andpractice of the present invention disclosed herein. It is intended thatthe specification and examples be considered as exemplary only, with thetrue scope of the present invention being indicated by the followingclaims.

We claim:
 1. A code reading apparatus comprising:illumination means forilluminating a code on a recording medium, on which audio informationdata is recorded as an optically readable code, by repeatedly emittinglight at predetermined intervals; image sensing means for receiving eachof light beams reflected by the recording medium including the codeilluminated by said illumination means in a read/scan operation for thecode, and for outputting a corresponding image sensing signal; signalprocessing means for decoding the audio information data by processingthe image sensing signal output from said image sensing means;reproduction output means for reproducing audio information based on theaudio information data decoded by said signal processing means, and foroutputting the audio information; supply voltage detection means fordetecting a supply voltage to a power supply circuit system including abattery used as a power supply of said apparatus; a power switch forturning on/off the supply voltage to said power supply circuit system;and detection timing control means for controlling said supply voltagedetection means to detect the supply voltage at a predetermined timingin an image sensing operation performed by said image sensing means at atime of light emission after the supply voltage to said power supplycircuit system is turned on by said power switch and a first lightemission is performed by said illumination means; wherein said imagesensing means includes a solid-state image sensing device for storing asignal charge corresponding to the light beams reflected by therecording medium by setting an exposure interval after an unnecessarycharge stored in a light-receiving section is removed, and fortransferring the stored signal charge from the light-receiving sectionto a light-shielding section after the exposure interval ends, therebyperforming an electronic shutter operation; and wherein said detectiontiming control means controls said supply voltage detection means todetect a supply voltage at a predetermined timing within a predeterminedinterval comprising an interval in which the unnecessary charge isremoved, the exposure interval, and an interval in which the signalcharge is transferred from the light-receiving section to thelight-shielding section.
 2. An apparatus according to claim 1, furthercomprising power supply inhibition means for inhibiting said powersupply circuit system including said battery from supplying power to acircuit system associated with said reproduction output means in a readinterval including the timing at which said supply voltage detectionmeans detects the supply voltage.
 3. An apparatus according to claim 1,wherein said detection timing control means controls said supply voltagedetection means to detect the supply voltage at a predetermined timingbefore the first light emission is performed by said illumination meansafter said power switch is turned on; andwherein said code readingapparatus further comprises warning means for generating a warning whena difference or ratio between a supply voltage detected by said supplyvoltage detection means at a predetermined timing before the firstemission and a supply voltage detected by said supply voltage detectionmeans at a predetermined timing after the first emission exceeds apredetermined level.
 4. An apparatus according to claim 1, wherein saiddetection timing control means controls said supply voltage detectionmeans to detect the supply voltage at a predetermined timing before thefirst light emission is performed by said illumination means after saidpower switch is turned on; andwherein said code reading apparatusfurther comprises power supply inhibition means for inhibiting saidpower supply circuit system from supplying power to at least one of saidillumination means and said image sensing means when a difference orratio between the supply voltage detected by said supply voltagedetection means at the predetermined timing before the first lightemission and the supply voltage detected by said supply voltagedetection means at a predetermined timing after the first light emissionexceeds a predetermined level.
 5. A code reading apparatuscomprising:illumination means for illuminating a code on a recordingmedium, on which audio information data is recorded as an opticallyreadable code, by repeatedly emitting light at predetermined intervals;image sensing means for receiving each of light beams reflected by therecording medium including the code illuminated by said illuminationmeans in a read/scan operation for the code, and for outputting acorresponding image sensing signal; signal processing means for decodingthe audio information data by processing the image sensing signal outputfrom said image sensing means; reproduction output means for reproducingaudio information based on the audio information data decoded by saidsignal processing means, and for outputting the audio information;supply voltage detection means for detecting a supply voltage to a powersupply circuit system including a battery used as a power supply of saidapparatus; a power switch for turning on/off the supply voltage to saidpower supply circuit system; and detection timing control means forcontrolling said supply voltage detection means to detect the supplyvoltage at a predetermined timing in an image sensing operationperformed by said image sensing means at a time of light emission afterthe supply voltage to said power supply circuit system is turned on bysaid power switch and a first light emission is performed by saidillumination means; wherein said image sensing means includes asolid-state image sensing device for storing a signal chargecorresponding to the light beams reflected by the recording medium bysetting an exposure interval after an unnecessary charge stored in alight-receiving section is removed, and for transferring the storedsignal charge from the light-receiving section to a light-shieldingsection after the exposure interval ends, thereby performing anelectronic shutter operation; and wherein said detection timing controlmeans controls said supply voltage detection means to detect a supplyvoltage at a predetermined timing within a predetermined intervalbetween an instant at which an image sensing signal is output from saidsolid-state image sensing device and a next unnecessary charge removalinterval.
 6. An apparatus according to claim 5, further comprising powersupply inhibition means for inhibiting said power supply circuit systemincluding said battery from supplying power to a circuit systemassociated with said reproduction output means in a read intervalincluding the timing at which said supply voltage detection meansdetects the supply voltage.
 7. An apparatus according to claim 5,wherein said detection timing control means controls said supply voltagedetection means to detect the supply voltage at a predetermined timingbefore the first light emission is performed by said illumination meansafter said power switch is turned on; andwherein said code readingapparatus further comprises warning means for generating a warning whena difference or ratio between a supply voltage detected by said supplyvoltage detection means at a predetermined timing before the firstemission and a supply voltage detected by said supply voltage detectionmeans at a predetermined timing after the first emission exceeds apredetermined level.
 8. An apparatus according to claim 5, wherein saiddetection timing control means controls said supply voltage detectionmeans to detect the supply voltage at a predetermined timing before thefirst light emission is performed by said illumination means after saidpower switch is turned on; andwherein said code reading apparatusfurther comprises power supply inhibition means for inhibiting saidpower supply circuit system from supplying power to at least one of saidillumination means and said image sensing means when a difference orratio between the supply voltage detected by said supply voltagedetection means at the predetermined timing before the first lightemission and the supply voltage detected by said supply voltagedetection means at a predetermined timing after the first light emissionexceeds a predetermined level.
 9. A code reading apparatuscomprising:illumination means for illuminating a code on a recordingmedium, on which audio information data is recorded as an opticallyreadable code, by repeatedly emitting light at predetermined intervals;image sensing means for receiving light beams reflected by the recordingmedium including the code illuminated by said illumination means in aread/scan operation for the code, and for outputting a correspondingimage sensing signal; signal processing means for decoding the audioinformation data by processing the image sensing signal output from saidimage sensing means; reproduction output means for reproducing audioinformation based on the audio information data decoded by said signalprocessing means, and for outputting the audio information; supplyvoltage detection means for detecting a supply voltage to a power supplycircuit system including a battery used as a power supply of saidapparatus; a power switch for turning on/off the supply voltage to saidpower supply circuit system; detection timing control means forcontrolling said supply voltage detection means to detect the supplyvoltage at a predetermined timing in an image sensing operationperformed by said image sensing means at a time of light emission afterthe supply voltage to said power supply circuit system is turned on bysaid power switch and a first light emission is performed by saidillumination means; and power supply inhibition means for inhibitingsaid power supply circuit system including said battery from supplyingpower to a circuit system associated with said reproduction output meansin a read interval including the timing at which said supply voltagedetection means detects the supply voltage.
 10. A code reading apparatuscomprising:illumination means for illuminating a code on a recordingmedium, on which audio information data is recorded as an opticallyreadable code, by repeatedly emitting light at predetermined intervals;image sensing means for receiving light beams reflected by the recordingmedium including the code illuminated by said illumination means in aread/scan operation for the code, and for outputting a correspondingimage sensing signal; signal processing means for decoding the audioinformation data by processing the image sensing signal output from saidimage sensing means; reproduction output means for reproducing audioinformation based on the audio information data decoded by said signalprocessing means, and for outputting the audio information; supplyvoltage detection means for detecting a supply voltage to a power supplycircuit system including a battery used as a power supply of saidapparatus; a power switch for turning on/off the supply voltage to saidpower supply circuit system; and detection timing control means forcontrolling said supply voltage detection means to detect the supplyvoltage at a predetermined timing in an image sensing operationperformed by said image sensing means at a time of light emission afterthe supply voltage to said power supply circuit system is turned on bysaid power switch and a first light emission is performed by saidillumination means; wherein said detection timing control means controlssaid supply voltage detection means to detect the supply voltage at apredetermined timing before the first light emission is performed bysaid illumination means after said power switch is turned on; andwherein said code reading apparatus further comprises warning means forgenerating a warning when a difference or ratio between a supply voltagedetected by said supply voltage detection means at a predeterminedtiming before the first light emission and a supply voltage detected bysaid supply voltage detection means at a predetermined timing after thefirst light emission exceeds a predetermined level.
 11. An apparatusaccording to claim 10, wherein said detection timing control meanscontrols said supply voltage detection means to detect the supplyvoltage at a predetermined timing in an image sensing operationperformed by said image sensing means at a time of each light emissionoperation after said power switch is turned on and the first lightemission is performed by said illumination means; andwherein saidwarning means generates the warning when a difference or ratio betweenthe supply voltage detected by said supply voltage detection means atthe predetermined timing before the first light emission and an averageof the supply voltages detected by said supply voltage detection means aplurality of number of times exceeds a predetermined level.
 12. Anapparatus according to claim 10, wherein said detection timing controlmeans controls said supply voltage detection means to detect the supplyvoltage a plurality of times at a high speed at a predetermined timingbefore the first light emission is performed by said illumination meansafter said power switch is turned on, and also controls said supplyvoltage detection means to detect the supply voltage a plurality oftimes at a high speed at a predetermined timing in an image sensingoperation performed by said image sensing means at the time of lightemission after said power switch is turned on and the first lightemission is performed by said illumination means; andwherein saidwarning means generates the warning when a difference or ratio betweenan average of the supply voltages detected by said supply voltagedetection means at the predetermined timing before the first lightemission and an average of the supply voltages detected by said supplyvoltage detection means at the predetermined timing after the firstlight emission exceeds a predetermined level.
 13. An apparatus accordingto claim 12, wherein said supply voltage detection means detects thesupply voltage to be detected the plurality of times at the high speedas digital data, and calculates the averages from the digital data. 14.An apparatus according to claim 10, wherein said detection timingcontrol means controls said supply voltage detection means to detect thesupply voltage at a predetermined timing in the image sensing operationperformed by said image sensing means at the time of each of a pluralityof light emission operations after said power switch is turned on andthe first light emission is performed by said illumination means;andwherein said warning means generates the warning when any one ofdifferences or ratios between the supply voltage detected by said supplyvoltage detection means at the predetermined timing before the firstlight emission and the supply voltages detected by said supply voltagedetection means the plurality of number of times exceeds a predeterminedlevel.
 15. An apparatus according to claim 10, wherein said detectiontiming control means controls said supply voltage detection means todetect the supply voltage at a predetermined timing in the image sensingoperation performed by said image sensing means at the time of each of aplurality of light emission operations after said power switch is turnedon and the first light emission is performed by said illumination means;andwherein said warning means generates the warning in accordance withthe number of times or the time during which a difference or ratio, ofdifferences or ratios between the supply voltage detected by said supplyvoltage detection means at the predetermined timing before the firstlight emission and the supply voltages detected by said supply voltagedetection means the plurality of number of times, which exceeds apredetermined level is detected.
 16. A code reading apparatuscomprising:illumination means for illuminating a code on a recordingmedium, on which audio information data is recorded as an opticallyreadable code, by repeatedly emitting light at predetermined intervals;image sensing means for receiving light beams reflected by the recordingmedium including the code illuminated by said illumination means in aread/scan operation for the code, and for outputting a correspondingimage sensing signal; signal processing means for decoding the audioinformation data by processing the image sensing signal output from saidimage sensing means; reproduction output means for reproducing audioinformation based on the audio information data decoded by said signalprocessing means, and for outputting the audio information; supplyvoltage detection means for detecting a supply voltage to a power supplycircuit system including a battery used as a power supply of saidapparatus; a power switch for turning on/off the supply voltage to saidpower supply circuit system; and detection timing control means forcontrolling said supply voltage detection means to detect the supplyvoltage at a predetermined timing in an image sensing operationperformed by said image sensing means at a time of light emission afterthe supply voltage to said power supply circuit system is turned on bysaid power switch and a first light emission is performed by saidillumination means; wherein said detection timing control means controlssaid supply voltage detection means to detect the supply voltage at apredetermined timing before the first light emission is performed bysaid illumination means after said power switch is turned on; andwherein said code reading apparatus further comprises power supplyinhibition means for inhibiting said power supply circuit system fromsupplying power to at least one of said illumination means and saidimage sensing means when a difference or ratio between the supplyvoltage detected by said supply voltage detection means at thepredetermined timing before the first light emission and the supplyvoltage detected by said supply voltage detection means at apredetermined timing after the first light emission exceeds apredetermined level.
 17. An apparatus according to claim 16, whereinsaid detection timing control means controls said supply voltagedetection means to detect the supply voltage at a predetermined timingin an image sensing operation performed by said image sensing means atthe time of each light emission operation after said power switch isturned on and the first light emission is performed by said illuminationmeans; andwherein said power supply inhibition means inhibits the supplyof power when a difference or ratio between the supply voltage detectedby said supply voltage detection means at the predetermined timingbefore the first light emission and an average of the supply voltagesdetected by said supply voltage detection means a plurality of timesexceeds a predetermined level.
 18. An apparatus according to claim 16,wherein said detection timing control means controls said supply voltagedetection means to detect the supply voltage, a plurality of times at ahigh speed at a predetermined timing before the first light emission isperformed by said illumination means after said power switch is turnedon, and also controls said supply voltage detection means to detect thesupply voltage a plurality of times at a high speed at a predeterminedtiming in an image sensing operation performed by said image sensingmeans at the time of light emission after said power switch is turned onand the first light emission is performed by said illumination means;andwherein said power supply inhibition means inhibits the supply ofpower when a difference or ratio between an average of the supplyvoltages detected by said supply voltage detection means at thepredetermined timing before the first light emission and an average ofthe supply voltages detected by said supply voltage detection means atthe predetermined timing after the first light emission exceeds apredetermined level.
 19. An apparatus according to claim 18, whereinsaid supply voltage detection means detects the supply voltage to bedetected the plurality of times at the high speed as digital data, andcalculates the average from the digital data.
 20. An apparatus accordingto claim 16, wherein said detection timing control means controls saidsupply voltage detection means to detect the supply voltage at apredetermined timing in an image sensing operation performed by saidimage sensing means at the time of each of a plurality of light emissionoperations after said power switch is turned on and the first lightemission is performed by said illumination means; andwherein said powersupply inhibition means inhibits the supply of power when any one ofdifferences or ratios between the supply voltage detected by said supplyvoltage detection means at the predetermined timing before the firstlight emission and the supply voltages detected by said supply voltagedetection means the plurality of times exceeds a predetermined level.21. An apparatus according to claim 16, wherein said detection timingcontrol means controls said supply voltage detection means to detect thesupply voltage at a predetermined timing in an image sensing operationperformed by said image sensing means at the time of each of a pluralityof light emission operations after said power switch is turned on andthe first light emission is performed by said illumination means;andwherein said power supply inhibition means inhibits the supply ofpower in accordance with the number of times or the time during which adifference or ratio, of differences or ratios between the supply voltagedetected by said supply voltage detection means at the predeterminedtiming before the first light emission and the supply voltages detectedby said supply voltage detection means the plurality of times, whichexceeds a predetermined level is detected.
 22. A code reading methodcomprising the steps of:illuminating a code on a recording medium, onwhich audio information data is recorded as an optically readable code,by repeatedly emitting light at predetermined intervals; receiving lightbeams reflected by the recording medium including the code in aread/scan operation for the code, and outputting a corresponding imagesensing signal; decoding the audio information data by processing theimage sensing signal; reproducing audio information based on the decodedaudio information, and outputting the information; detecting a supplyvoltage to a power supply circuit system including a battery used as apower supply; turning on/off the supply voltage to said power supplycircuit system; and controlling detection of the supply voltage at apredetermined timing in an image sensing operation at a time of lightemission after the supply voltage to said power supply circuit system isturned on and a first light emission is performed; wherein a solid-stateimage sensing device is controlled to store a signal chargecorresponding to the light beams reflected by the recording medium bysetting an exposure interval after an unnecessary charge stored in alight-receiving section is removed, and to transfer the stored signalcharge from the light-receiving section to a light-shielding section,thereby performing an electronic shutter operation; and whereindetection of the supply voltage is controlled to occur at apredetermined timing within a predetermined interval comprising aninterval in which the unnecessary charge is removed, the exposureinterval, and an interval in which the signal charge is transferred fromthe light-receiving section to the light-shielding section.
 23. A methodaccording to claim 22, further comprising the step of inhibiting saidpower supply circuit including said battery from supplying power to acircuit system associated with reproduction and output of the audioinformation during a read/scan interval for the code, which includes thetiming at which the supply voltage is detected.
 24. A code readingmethod comprising the steps of:illuminating a code on a recordingmedium, on which audio information data is recorded as an opticallyreadable code, by repeatedly emitting light at predetermined intervals;receiving light beams reflected by the recording medium including thecode in a read/scan operation for the code, and outputting acorresponding image sensing signal; decoding the audio information databy processing the image sensing signal; reproducing audio informationbased on the decoded audio information, and outputting the information;detecting a supply voltage to a power supply circuit system including abattery used as a power supply; turning on/off the supply voltage tosaid power supply circuit system; and controlling detection of thesupply voltage at a predetermined timing in an image sensing operationat a time of light emission after the supply voltage to said powersupply circuit system is turned on and a first light emission isperformed; wherein a solid-state image sensing device is controlled tostore a signal charge corresponding to the light beams reflected by therecording medium by setting an exposure interval after an unnecessarycharge stored in a light-receiving section is removed, and to transferthe stored signal charge from the light-receiving section to alight-shielding section after the exposure interval ends, therebyperforming an electronic shutter operation, and wherein detection of thesupply voltage is controlled to occur at a predetermined timing within apredetermined interval between an instant at which an image sensingsignal is output from said solid-state image sensing device and a nextunnecessary charge removal interval.
 25. A method according to claim 24,further comprising the step of inhibiting said power supply circuitincluding said battery from supplying power to a circuit systemassociated with reproduction and output of the audio information duringa read/scan interval for the code, which includes the timing at whichthe supply voltage is detected.
 26. A code reading method comprising thesteps of:illuminating a code on a recording medium, on which audioinformation data is recorded as an optically readable code, byrepeatedly emitting light at predetermined intervals; receiving lightbeams reflected by the recording medium including the code in aread/scan operation for the code, and outputting a corresponding imagesensing signal; decoding the audio information data by processing theimage sensing signal; reproducing audio information based on the decodedaudio information, and outputting the information; detecting a supplyvoltage to a power supply circuit system including a battery used as apower supply; turning on/off the supply voltage to said power supplycircuit system; controlling detection of the supply voltage at apredetermined timing in an image sensing operation at a time of lightemission after the supply voltage to said power supply circuit system isturned on and a first light emission is performed; and inhibiting saidpower supply circuit including said battery from supplying power to acircuit system associated with reproduction and output of the audioinformation during a read/scan interval for the code, which includes thetiming at which the supply voltage is detected.